PGRS Flashcards
Dehydrins are proteins that accumulate in seeds during the later stages of their development or maturation. Their accumulation is stimulated by the plant hormone called ______.
ABA
Accumulation of dehydrins allows seeds to tolerate _____ because dehydrins are highly _____ which helps maintain the adequate amount of ______.
dehydration tolerance; hydrophilic; water
What is “crown gall” of plants?
it is a tumor on plants
how does Agrobacterium cause crown gall
it tricks the plant cells into playing a host for the bacteria
what are the steps of crown gall formation
- bacteria infects the crown cells
- transfers its genes into plant cell’s DNA (trick)
- infected cells provide an expanding for bacteria to thrive
Cytokinins
B. promote axilary branching in tissue cultures and delay senescence of leaves
As dormant seeds come out of dormancy as a result of “moist-chilling” exposure, following happens to the levels of the two hormones:
B. GA, a growth promoter, accumulates while ABA, a growth retardant decreases
Define VIVIPARY
a phenomenon where seeds precociously germinate
why does VIVIPARY occur
it is a genetic mutation and when it has been found in corn there is a reduced production of ABA
many PGRs are used in commercial hort as sprays/drench application to regulate plant height. they do so by:
inhibiting GA production
a growth regulator that is often used as a spray on grape clusters to achieve
larger fruit
the regulator used in grape clusters does so by
Pro-Gibbs elongate the flower stalks and spreads the flowers out and it allows for larger fruit development
treatment of shade trees with Paclobutrazol not only controls their height but often results in darker green leaves compared to untreated ones. Give one bio chem explanation of this
because there are smaller cells there are more cells per unit area. this means there are also greener leaves
GA application promotes
maleness
list all steps in the mechanism of stomate closure involving ABA
- ABA enters guard cells
- loss of K+
- water flows out of guard cells to maintain equilibrium
- Loss of turgor-pressure in guard cells
- Stomata close
which hormone plays an important role in apical dominance and how
auxin inhibits the axillary branching by overcoming the effects of cytokinin
what is witches broom
extreme axillary branching; apical dominance is countered but the lateral buds go crazy as well
what is the hormonal explanation for witches brooming
overproduction of cytokinins that out competes the auxins that would promote apical dominance
provides steps of why GA plays important role in food mobilization during seed germination
- GA synthesized in the embryo after imbibition
- diffuses to aleurone and stimulates (roman)a-amylase enzyme
- a-amylase activated and released in endosperm
- breakdown of starch by a-amylase
- sugars mobilized to meet the demand by germinating seed
PGR that mimics what hormone sprayed on grapes
Gibberelin
what PGR mimics gibberelins and is sprayed on grapes
PRO-GIBB
what hormone promoted maleness
GA
Green revolution bonus
Norman Borlaug used mutated DELLA protein to promote dwarfism in wheat. The mutated DELLA is not usually recognized by GA which usually degrades it and promotes growth. This prevented lodging in wheat which resulted in the loss of seeds before harvest. He won a nobel prize for this work
